Сontrolling stress state of a hoisting shaft frame in the context of specific freezing process

Abstract

Purpose is to obtain regularities of a stress state of such multilayer system as neighbourhood rock mass -frozen soilhoisting shaft frame in the process of numerical analysis to control a frame state with the selection of efficient parameters; thickness depending upon a specific frozen process specifically.Methods. Numerical analysis on the basis of a finite-element method has been implemented relying upon Pro Complex Structure CAD for Windows (SCAD) which made it possible to obtain stress state of a hoisting shaft frame and its interaction with ice-soil blocking as well as with neighbourhood rock mass soil.Findings. Hoisting shaft model has been developed. The model is based upon actual geometry and results of laboratory studies. Three blocking types (i.e. reinforced-concrete blocks, gray cast-iron tubbings, and modified gray castiron tubbings) and two soil types (i.e. sand and clayish soil at +8°С temperature) in terms of different freezing temperatures (i.e. (-2, -6 and -10°С) were analyzed numerically with the use of the SCAD. Results of the research have helped identify dependences concerning formation of a stress state of the multilayer neighbourhood rock massfrozen soil -hoisting shaft frame system while varying properties of the listed types of a frame, neighbourhood rock mass, and ice-soil blocking. Regularities of the stressed state components deepening upon the frozen soil elasticity modulus, corresponding to its certain temperature, and elasticity modulus of a hoisting shaft frame have been obtained. The regularities connect changes in the stress of a hoisting shaft blocking in the context of specific freezing process.Originality. The obtained dependences of the stressed state of a hoisting shaft frame on the soil elasticity modulus and the material are composite spatial surfaces reflecting representatively the stressed state of such multilayer systems as neighbourhood rock mass -frozen soil -hoisting shaft frame.Practical implications. The regularities of the stressed state, determined for such multilayer systems as neighbourhood rock mass -frozen soil -hoisting shaft frame, make it possible to control stress components selecting rational geometry of a frame and its material or temperature cycle to freeze soils while applying the specific method.

Nonuniform stress state of a hoisting shaft lining as a result of disturbance of the ground freezing technology

“…This complex, labor-consuming and expensive method of maintaining the working in a stable state has a significant advantage, which other ones do not have: it is guaranteed to retain underground water outside of ice-ground blocking [2,4]. In the active stage of freezing, when a stable negative temperature is maintained in blocking, stress state of the multilayer "surrounding massif ground-frozen ground-hoisting shaft lining" system remains stable, which is confirmed by the conducted research [2,5,6]. In the paper [6], the authors proposed to control stress state of the lining with the selection of effective parameters (for example, thickness), depending on the parameters of the special method of freezing.…”

“…Undoubtedly, the research of a hoisting shaft should be carried out only with the use of a spatial model, since forming stress state applies to all its components. Such a model, based on the finite-element technique, had already been created earlier and widely tested in a number of studies of hoisting shafts [6][7][8]. It is this indicated model that allowed to study stress state of the shaft in the process of freezing and offer stress state control basics of the lining with the selection of effective parameters [6].…”

“…Such a model, based on the finite-element technique, had already been created earlier and widely tested in a number of studies of hoisting shafts [6][7][8]. It is this indicated model that allowed to study stress state of the shaft in the process of freezing and offer stress state control basics of the lining with the selection of effective parameters [6]. The following research also applies this model, which is based on volumetric finite elements and simulates a hoisting shaft with a depth of 40 meters and an internal diameter of 5.1 m [6] (Fig.…”

“…At the qualitative analysis of the stress state results, characteristic patterns of stresses in the shaft mouth and in the base of a hoisting shaft can be noted. Compared to the isofields of horizontal stresses in the linings at uniform freezing [6,8], the maxima of the nonuniform freezing isofields are strongly displaced towards the defrosted grounds and are strongly elongated, at this the shorter part of the isofield is always located at the side of the ground with a greater elasticity modulus, that is, the frozen part. In the lowest isofield, which has the wrong shape, the greatest normal horizontal stresses are observed.…”

Comparative Analysis of Special Methods During Vertical Works

“…2) які знижують рухливість цих ґрунтів на певний період часу (штучне заморожування ґрунтів) (Andersland, & Ladanyi, 2003;Tiutkin, Petrenko, Petrosian, Miroshnyk, & Alkhdour, 2018;Дорман, 1971);…”